Initial Celery setup.

Celery is setup in two parts, first on app initialization for usage
in the app, and second in fanboi2.scripts.celery as a wrapper for
"celery" script to make it behave the same way as other Pyramid scripts
(i.e. "celery config.ini command").

Both setup are done via fanboi2.tasks:configure_celery which initialize
configuration from Pyramid settings dict.
Setup Celery provisioning using Supervisord.

Reuse existing Supervisord setup in development but add Celery
configuration to it.
Move topic posting and topic replying stuff into task queue.

* Setup Akismet key on startup instead of via request.
* Move __VERSION__ to fanboi2.version so task queue could access it.
* No longer requiring a real pyramid.util.Request for fanboi2.utils.

This commit moves all the post and topic creation code to task queue
in order to prevent blocking of worker when a post is made. Worker
need to connect to Akismet, which may cause worker to be blocked up
to few seconds depending on network condition.

The implement is still incomplete, as there is no feedback after the
posting is done. Only a dumb redirect.
Quick cleanups.
Handle post status reporting with task status page.

Since we don't know when will the post succeed, a new page is added
for querying post status every 1 second. If the post is succeed,
user will be redirected to the appropriate path automatically.
Use BaseTaskView instead of dedicated TaskView.

Since we need to render different template for each task status, using
another request dispatcher to handle task and reuse the post URL makes
more sense in a long run.
Handles periodic checking for task status in JavaScript component.
Fix posts bumping no longer working.
Update test cases for existing failing specs.

This includes fanboi2.utils and fanboi2.views. Since we've moved all
posting logic into fanboi2.tasks, now the actual post insertion in
view spec are stubbed out (and will be tested in tasks spec).
Add test case for tasks stuff.
Merge branch 'feature/post-worker' into develop